Gene-based approaches to the treatment of disease are theoretically straightforward; reduction to practice, however, has proven to be an extraordinary complex undertaking that requires the expertise of many different individuals. We propose a unique individualized training program in clinical gene therapy. The goal of the training of the training program will be to graduate rigorous and outstanding post doctoral fellows into independent investigators who will continue to advance the field of gene therapy. We will offer two years of funded educational training for two PEGT funded trainees (one each at Stanford and CHOP/Penn). The training will be open to individuals with an MD, MD/PhD or PhD. The successful trainees accepted into the program will spend at least 25% of their effort on one of the clinical trials directed at gene-based therapies for hemophilia. The remainder of their time can be spent on some combination of basic/preclinical research, clinical trials, data management design. Unique didactic educational opportunities are available at each institution as outlined as part of the training. Each potential candidate will be evaluated by the Internal Advisory Committee members and decision for funding will be made by conference call consensus. The program in Philadelphia will e overseen jointly by Drs. High and Kazazian while the program at Stanford University will be overseen jointly by Dr. Kay. An ongoing purpose of the training program is the establishment of a close relationship with mentors and other members of the faculty who can provide guidance to the fellow as he/she seeks additional funding and a position as an independent investigator.